The present invention relates to an article transporting apparatus and its operating method. More particularly, this invention relates to an article transporting apparatus including a plurality of movable bodies for transporting articles, the movable bodies being movable between a plurality of article transfer locations and an operation controlling means for controlling the plurality of movable bodies so that the movable bodies effect article transporting operations in accordance with an article transport request information.
With the article transporting apparatus of the above type, each one of the plurality of article transporting bodies is movable between a plurality of article transfer locations for effecting an article transporting operation. As article transporting operations are effected with using the plurality of such movable bodies, the apparatus can achieve improved transporting ability.
According to a known article transporting apparatus of this type, a pair of movable bodies are adapted to be movable along a same track and the operation controlling means is configured to select both or one of the paired movable bodies for an article transporting operation(s) (see e.g. Japanese Patent No. 2857836).
The article transporting apparatus disclosed in the above document includes some equipments (replaceable components or parts) such as a sensor, a brake, etc. which are worn with implementation of each article transporting operation. As these equipments are worn with use, they need to be replaced by new ones before expiration of their service lives. Then, when the used period of such equipment reaches a predetermined period, this equipment is replaced by a new one. For this replacement, a movable body including this particular equipment is temporarily put out of its article transporting service and moved to an evacuation area, where the replacement operation of the equipment is effected.
In the case of the article transporting apparatus known from the above document, its operation controlling means is adapted simply for selecting one or both of paired movable bodies to cause it or them to effect an article transporting operation, based on article transport request information. Hence, it can sometimes happen that the two movable bodies have same past operation history such as a same number of article transporting operations which have been effected respectively thereby.
If this happens, the used periods of the equipments (replaceable parts) of these two movable members are identical, thus, the replacement timings thereof are set same. Therefore, both movable bodies will be temporally put out of the article transporting service to allow the replacement operations of the equipments of these two movable bodes to be effected at one time.
The above situation can be a problem with some systems employing such article transporting apparatus which need to effect article transporting operations constantly in a continuous manner without any interruption or suspension thereof. The above-described conventional apparatus may not satisfy this need.
On the other hand, in some cases, if replacement timings of their equipments differ from each other among a plurality of movable bodies, this can make the replacement operations troublesome. In such case, it is desired for the replacement timings of the equipments of the movable bodies to coincide with each other.